南师大锅炉原理课件3-1 燃料的燃烧计算

2025/6/2213.1Fuelcombustioncalculation

§3-1燃料的燃烧计算Basicassumption

基本假设：Airandfluegasareidealgases,andthevolumeofanidealgasdirectlyproportionaltoitsabsolutetemperatureandinverselyproportionaltoitsabsolutepressure.Thevolumeofonekmolofanidealgasis22.4Nm3atstandardcondition(0ºC,1atm). 空气、烟气均为理想气体，每kmol体积等于22.4Nm3；Onlyoxygenandnitrogeninair,andthevolumeratioofoxygentonitrogenis21:79. 空气中只有O2和N2成分，其容积比为：21:79.Fuelcombustioncalculationisundertheconditionofcompletecombustion. 每kg燃料都是在完全燃烧的条件下计算。2025/6/2223.1Fuelcombustioncalculation

§3-1燃料的燃烧计算1.Theoreticalairrequirement

理论空气量计算Theoreticalairistheminimumairrequiredforcompletecombustionoffuel,i.e.theoxidationofcarbontoCO2,Hydrogentowatervapor(H2O),andsulfurtosulfurdioxide.Condition:

completecombustionandnoexcessoxygen. 燃料完全燃烧且无余氧。Calculationprinciple:thesupplyingO2isthetotaloxygenoffuelcompletecombustionsubtractingtheoxygenboundinfuel,andthecalculatingthetheoreticalairrequirement. 计算的基本原理：燃料完全燃烧需要的总氧量减去燃料自身所含氧量为外界供氧量，然后折算出理论空气量。Solid&liquidfuels固体及液体燃料完全燃烧需要的理论空气量计算Gaseousfuels气体燃料完全燃烧需要的理论空气量计算2025/6/2233.1Fuelcombustioncalculation

§3-1燃料的燃烧计算1.Theoreticalairrequirement

理论空气量的计算

C+O2＝CO2S+O2＝SO22H2+O2=2H2O1kmol12kg22.422.432kg22.422.42X2.016kg22.42X22.4C,S,H:2.01611.222.41kgC,S,H1kg22.4/121kg22.4/321kg22.4/4.032Nm3/kg1.8661.8660.70.75.5511.11kgfuel1.866Car/1000.7Sar/1005.55Har/100消耗的O22025/6/2243.1Fuelcombustioncalculation

§3-1燃料的燃烧计算1.Theoreticalairrequirement

理论空气量计算Theoreticalairrequirementofcompletecombustionofsolid/liquidfuel固体燃料完全燃烧需要的理论空气量Convertingtomassbasis:multiplyairdensityof1.293 换算为质量时，乘以空气的密度1.293kg/Nm3即可得：Calculatedbynextequationwithoutultimateanalysisofafuel 在缺少燃料元素成份时，理论空气量可用下式近似计算：2025/6/2253.1Fuelcombustioncalculation

§3-1燃料的燃烧计算1.Theoreticalairrequirement

理论空气量的计算Theoreticalairrequirementofgaseousfuel

completecombustion气体燃料完全燃烧需要的理论空气量计算Forgaseousfuel对气体燃料成份不用重量百分比(Percentbyweight)，只用干燥的气体中各种成份的容积百分比(Percentbyvolume)来表示，计算相对容易。2025/6/2261.Theoreticalairrequirement

理论空气量的计算(PP.10-15)Forcommercialapplications,morethantheoreticalairisneededtoassurecompletecombustion.Thisexcessairisneededbecausetheairandfuelmixingisnotperfect.Becausetheexcessairthatisnotusedforcombustionleavestheunitatstacktemperature,theamountofexcessairshouldbeminimized.

Theenergyrequiredtoheatthisairfromambienttostacktemperatureusuallyservesnopurposeandislostenergy.Typicalvaluesofexcessairrequiredattheburningequipmentareshownin

Table11

forvariousfuelsandmethodsoffiring.3.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2025/6/2272025/6/2281.Theoreticalairrequirement

理论空气量的计算(PP.10-15)Theamountofexcessairattheexitofthepressureparts(whereitisusuallymonitored)mustbegreaterthantheairrequiredattheburningequipmenttoaccountforsettinginfiltrationonbalanceddraftunits(orsealaironpressure-firedunits).Onmodernunitswithmembranewallconstruction,thisisusuallyonly1~2%excessairatfullload.Onolderunits,however,settinginfiltrationcanbesignificant,andoperatingwithlowairatthesteamgeneratorexitcanresultininsufficientairattheburners.Thiscancausepoorcombustionperformance.3.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2025/6/2293.1Fuelcombustioncalculation

§3-1燃料的燃烧计算1.Theoreticalairrequirement

理论空气量的计算1)Excessairratio过量空气系数αTheratioofactualair,Vaandtheoreticalair,Va,0(Nm3/kg) 实际空气量与理论空气量比值.

excessaircoefficient

excessairfactor

Whichdependsoncombustionequipment,fueltype,andcombustionmethod(Seetable11). 与燃烧设备、燃料种类、燃烧方式等有关(见前Table11)。stocker层燃炉:α“=1.3~1.4；suspensionfurnace室燃炉:α”=1.05~1.10；

PCboiler煤燃烧一般炉膛出口处α“=

1.15～1.352025/6/22103.1Fuelcombustioncalculation

§3-1燃料的燃烧计算1.Theoreticalairrequirement

理论空气量的计算2)

Actualair(completecombustion)实际空气量(完全燃烧)(Nm3/kg)2025/6/22113.1Fuelcombustioncalculation

§3-1燃料的燃烧计算1.Theoreticalairrequirement

理论空气量的计算3)Airleakagefactor漏风系数Δα(pp.27表2-4)Theratioofair-leakagerate

totheoreticalairofunitfuel. 1kg燃料，漏入空气量ΔV与理论空气量Va,0的比值。锅炉运行时，炉中处于负压工作状态，炉外冷空气从炉墙、门孔几个受热面贯穿墙处漏入炉内，使炉内过量空气系数沿烟气流程逐渐增大。各受热面漏风量：

Nm3/kg2025/6/22123.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2.Fluegasvolumecalculation烟气量计算Fluegasconstituentofsolid/liquidfuelscombustion 固体燃料及液体燃料的燃烧后生成的烟气成分(1)α＝1,completecombustion,fluegascomposition完全燃烧，烟气成份：

CO2﹑SO2﹑H2O﹑Ｎ2

；(2)α＞1,completecombustion：

CO2﹑SO2﹑H2O﹑Ｎ2﹑O2；(3)α≥1,incompletecombustion

且不完全燃烧

CO2﹑SO2﹑H2O﹑Ｎ2﹑O2

﹑CO；(4)α＜1，incompletecombustion：

CO2﹑SO2﹑H2O﹑Ｎ2﹑CO2025/6/22133.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2.Fluegasvolumecalculation烟气量计算Fluegasconstituentofsolid/liquidfuelscombustion1)

Theoreticalfluegasvolume

理论烟气量计算Condition：α＝1,completecombustion完全燃烧：Fluegascomposition:CO2﹑SO2﹑H2O﹑N2(1)

Volumeoftriatomicgasinfluegas

三原子气体体积： ＲO2＝CO2+SO2； VＲO2＝VCO2+VSO22025/6/22143.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2.Fluegasvolumecalculation烟气量计算1)

Theoreticalfluegasvolume理论烟气量计算(2)

H2Ovolumeintheoreticalfluegas

理论烟气中水蒸汽体积H

contentinfuelMoistureinfuelMoistureinairAtomizationwater空气含湿量：10g/kg干空气密度：1.293kg/Nm3水蒸气比容：1.24Nm3/kgNm3/kg2025/6/22153.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2.Fluegasvolumecalculation烟气量计算1)

Theoreticalfluegasvolume理论烟气量计算(3)

N2volumeintheoreticalfluegas

理论烟气中氮气体积N2inair空气中的氮气:0.79V0Fuel-N燃料本身含氮:2025/6/22163.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2.Fluegasvolumecalculation烟气量计算1)

Theoreticalfluegasvolume

理论烟气量计算(4)Theoreticalfluegasvolume

理论烟气量

Vdf,0——theoreticaldryfluegasvolume理论干烟气体积2025/6/22173.1Fuelcombustioncalculation

§3-1燃料的燃烧计算2.Fluegasvolumecalculation烟气量计算2)

Actualfluegasvolume

实际烟气量计算Condition:

α>1,completecombustion完全燃烧Fluegascomposition:CO2﹑SO2﹑H2O﹑N2﹑O2O2inexcessair过量空气中氧容积：Nm3/kgN2inexcessair过量空气中氮容积：Nm3/kgH2Oinexcessair过量空气中水蒸汽容积：Nm3/kgActualfluegasvolume=theoreticalfluegasvolume+excessair2025/6/22183.1Fuelcombustioncalculation

§3-1燃料的燃烧计算3.Enthalpyofairandgluegas空气与烟气的焓1)Enthalpyoftheoreticalair

理论空气焓Definition:Theessentialheatquantityoftheoreticalairvolumeofaunitsolid(liquid)fuelisheatedfrom0ºCtoθºCataconstantpressure. 定义：每kg固体(液体)燃料燃烧所需的理论空气量，在等压下从0℃加热到℃时所需的热量。

kJ/kgSpecificheat2025/6/22193.1Fuelcombustioncalculation

§3-1燃料的燃烧计算3.Enthalpyofairandgluegas空气与烟气的焓2)Enthalpyoftheoreticalfluegas

理论烟气焓：Definition：Theessentialheatquantityoftheoreticalfluegasvolumeproducedbya